A gas turbine includes a compressor configured to compress atmospheric air to generate compressed air, combustors configured to burn a fuel in the compressed air to generate a combustion gas, and a turbine driven using the combustion gas. Hot parts coming into contact with the high temperature combustion gas among parts constituting the gas turbine need to be cooled using any method to improve their durability. Examples of hot parts include vanes, blades, and the like of the turbine.
The following Patent Document 1 discloses a cooling system configured to cool a hot part of a gas turbine using air bled from a compressor. This cooling system includes a rotor cooling air line (a high pressure bleed line) configured to send air to blades in a turbine rotor, a vane cooling air line (a low pressure bleed line) configured to send air to vanes in a turbine, and a communicating line (a connecting line) configured to connect the rotor cooling air line and the vane cooling air line. The rotor cooling air line bleeds air from a first bleed position of a compressor and sends the air to the blades in the turbine rotor constituting some of hot parts. The vane cooling air line bleeds air at a pressure lower than that of the air winch is bled from the first bleed position from a second bleed position of the compressor and sends the air to the vanes in the turbine. A cooler configured to cool air passing through the rotor cooling air line is provided at a position in the rotor cooling air line closer to the first bleed position side than a position of connection with the communicating line. A control valve configured to adjust a flow rate of air flowing through the vane cooling air line is provided at a position in the vane cooling air line closer to the vane side than a position of connection with the communicating line. A control valve configured to adjust a flow rate of air flowing through the communicating line is provided in the communicating line.
In this cooling system, the control valve provided in the communicating line is opened so that high pressure air bled from the first bleed position and cooled by the cooler can flow into the vane cooling air line.